The present invention relates to systems and methods for measuring the thickness of flat sheet products. More particularly, the present invention relates to a system and method for frequent and accurate measuring of flat sheet thickness on a process line to control the sheet production process. The system and method of the present invention comprise software applications for collecting and analyzing measurement data and providing the results to a process control system that controls the production process.
Flat sheet products such as steel and aluminum are generally produced by a rolling process. Plastic sheet products may be produced using an extrusion or molding process. Regardless of the material, the resulting flat sheet product is typically much longer and wider than it is thick. Purchasers of flat sheet products such as metal and plastic sheets must be assured that the product meets various quality specifications and standards. In most instances, it is important that the thickness of a flat sheet product be within a very narrow tolerance across the length and width. Automated systems and methods for measuring and monitoring thickness during a mill or rolling process have been developed. However, the systems and methods that are used currently support limited sampling and testing during the production process. As a result, a product that does not meet specified tolerances and standards may be produced without the manufacturer""s knowledge.
In some cases, sampling does not occur frequently enough to detect non-conformances. At the time the samples are taken, the thickness appears to be uniform and consistent because it is within specified tolerances or standards. The non-conformances may occur between samples such that the measuring and monitoring processes do not detect the problems. Even if a system and method support frequent sampling of data related to the production process, the system or method may not be able to determine quickly enough the extent of the non-conformance so that the production process may be controlled appropriately. Thickness values are typically approximated based on data in a lookup table and therefore, are not precise. The inability to determine quickly and accurately the differences between the actual and target measurements for the sheet product thickness may result in excessive scrap, wasted production time, and possibly, rejection of the final product by the customer. Therefore, there is a need in the flat sheet production process to accurately and quickly measure the thickness of the sheet and to provide an output to a process control system to the control the thickness of the sheet during the production process.
The present invention is a system and method that supports frequent and accurate measuring of flat sheet thickness on a process line to control the flat sheet production process. Results of the monitoring process of the present invention may be communicated to a process control system used to adjust the production process. Data collection and data analysis are accomplished using a plurality of software applications in communication with various devices and equipment that support the collection and analysis functions of the present invention.
The present invention may be implemented with industry standard hardware, software, and a personal computer integrated with custom software. The present invention comprises a source/detector unit, frame, or other production device for collecting data during the production process. The data is transmitted to a calculation device, such as a data acquisition processor (DAP) board, for processing. In an example embodiment of the present invention in which a DAP board is used, the measured data is manipulated, analyzed, and compared for conformance to certain specifications or tolerances. In the event the thickness of the sheet product is outside the specifications or tolerances, several actions may be taken. First, an alarm may be triggered to notify an operator or quality control specialist that the sheet thickness values are outside a specified tolerance. Data related to the calculated thickness values may be recorded. Error signal outputs may be communicated to a process control system to allow corrective actions to be taken. Additional commands may be communicated to various pieces of equipment or specific devices on the production floor. Production data may further be communicated to another production floor computer for further analysis and long-term storage. Software applications executing at the production floor computer may be used by an operator to perform setup and configuration operations for various pieces of production equipment and devices that comprise the present invention as well as to control the production process when the production equipment and devices are operational. An interactive graphical display facilitates an operator""s interaction with the various software applications. The software applications support automation of the production process so that the resulting flat sheet is more likely to conform to the applicable specifications or tolerances. The system is configurable for different processing environments and flat sheet compositions.